Transcatheter valve stent anchors

ABSTRACT

A stent for use in a prosthetic heart valve has a plurality of expandable and collapsible closed cells, a portion of which form an annulus section adapted for placement within the annulus of the native heart valve. Anchor features of the stent residing within at least some closed cells are adapted to engage tissue of the heart, including native valve leaflets, the sinotubular junction, or another implanted device when the prosthetic valve is implanted in the heart. The anchor features may help to retain the prosthetic valve in position, without interfering with the opening and closing of the valve leaflets. Furthermore, the anchor features may be configured to allow the stent to be resheathed into a delivery device after the portion of the stent with the anchor feature has expanded out of the delivery device.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 14/164,611, filed Jan. 27, 2014, which claims the benefit ofthe filing date of U.S. Provisional Patent Application No. 61/766,783filed Feb. 20, 2013, the disclosures of which are both herebyincorporated by reference herein.

FIELD OF THE INVENTION

The present invention is directed to prosthetic heart valves forreplacement of native heart valves, to stents for use in such prostheticheart valves, and to methods of treating patients with such prostheticheart valves.

BACKGROUND OF THE INVENTION

Certain prosthetic heart valves incorporate an expandable stent body andvalve elements such as prosthetic valve leaflets mounted to the stentbody. Valves of this type may be implanted in the heart by advancing thevalve into the body of the patient with the stent body in a collapsedcondition in which the stent body has a relatively small diameter. Oncethe valve is positioned at the desired implantation site, the stent bodyis brought to an expanded condition in which the stent body bears on thesurrounding native tissue and holds the valve in place. The valve actsas a functional replacement for the diseased native valve. Thus, thevalve elements inside the stent body permit blood flow in the antegradedirection but substantially block flow in the opposite, retrogradedirection. For example, a prosthetic valve may be advanced to a sitewithin a diseased native aortic valve percutaneously through thearterial system and into the aorta to the native aortic valve. In atransapical placement, a prosthetic valve may be advanced through anincision in the apex of the heart and through the left ventricle to thenative aortic valve. Other approaches through other access sites can beused. Once the prosthetic valve is in place, it permits flow from theleft ventricle into the aorta when the left ventricle contracts duringsystole, but substantially blocks retrograde flow from the aorta intothe left ventricle during diastole.

There are significant challenges in the design of an expandable stentbody and valve. For example, the stent body desirably can be collapsedto a relatively small diameter to facilitate advancement into the body.However, the stent body must be capable of expanding to an operative,expanded condition in which the stent body securely engages thesurrounding native tissues to hold the valve in place. The valve shouldform a good seal with the surrounding native tissues to prevent leakagearound the outside of the prosthetic valve, commonly referred to asperivalvular leakage. The stent body, in its expanded, operativecondition, desirably does not apply excessive forces to the annulus ofthe native valve. Excessive forces on the annulus of the native aorticvalve can disrupt the electrical conduction system of the heart and alsocan impair the functioning of the mitral valve. These issues arecomplicated by the fact that the native valve leaflets ordinarily areleft in place when an expandable prosthetic valve is implanted. Thediseased native valve leaflets and other diseased tissues may present animplantation site which is irregular. For example, patients withcalcified or stenotic aortic valves may not be treated well with thecurrent collapsible valve designs, and may encounter problems such as(1) perivalvular leakage (PV leak), (2) valve migration, (3) mitralvalve impingement, (4) conduction system disruption, etc., all of whichcan lead to adverse clinical outcomes. To reduce these adverse events,the optimal valve would seal and anchor adequately without the need forexcessive radial force that could harm nearby anatomy and physiology.

As the patient population becomes younger with less tissuecalcification, the use range of prosthetic heart valves expands tolarger sizes and thus greater forces. Additionally, younger patients maybe more likely to require bicuspid valve replacements and may havelarger, more diseased, and more elliptically shaped aortic valves. Stentdesigns without an aortic section, as well as stents that need to anchorin the aorta, will need to anchor and support post deflection of thevalve as it pulls inward from pressure closing the valve. If a valve isnot designed to function in these environments, it may result in severaltypes of adverse events described above since distortion of the valvecan result in the loss of valve coaptation, loss of valve apposition,and overall higher stresses. In these environments, anchoring willbecome even more important to ensure valve coaptation in most allconfigurations with a reduction of high stresses in the critical areasof the prosthesis while maintaining valve apposition with nativeanatomy.

Numerous prosthetic valve and stent body designs have been proposed.However, despite all of the attention devoted to such designs, stillfurther improvements would be desirable.

BRIEF SUMMARY OF THE INVENTION

A stent for use with a prosthetic heart valve for replacement of anative heart valve comprises an expandable stent body having a collapsedconfiguration and an expanded configuration. The stent body includes aplurality of closed cells and at least one anchor feature formedintegrally with the stent. Each anchor feature resides within a closedcell of the stent and has an engagement portion adapted to engage asurface in a heart.

The engagement portion can be configured to engage any combination of aleaflet of the native heart valve, a portion of the sinotubular junctionin the heart, and a portion of another device already implanted in theheart.

The stent is arranged in the collapsed configuration when receivedwithin a delivery sheath overlying the stent in a sheathed position, andthe stent is arranged in the expanded configuration when the sheath isnot overlying the stent in an unsheathed position. The anchor feature isoriented at an oblique angle to a longitudinal axis of the deliverysheath so that the stent may be resheathed when the sheath is in aposition between the sheathed position and the unsheathed position. Theanchor feature slopes radially outwardly from the stent when the stentis in the expanded configuration, and the anchor feature extends axiallywhen the stent is in the collapsed configuration.

The engagement portion of the anchor feature can include an anchor tipwith a first end connected to the stent, a second end connected to thestent, and an intermediate portion between the first and second ends.The intermediate portion of the anchor tip can include a single piecethat is acute or blunted. The intermediate portion of the anchor tip canalternately include multiple separate pieces. These separate pieces caninclude different configurations, such as blunted ends.

The stent can include a first annular row of cells connected to a secondannular row of cells by at least one connector. The anchor feature isconnected to the connector. The connector can be a commissure attachmentfeature. The anchor features can be connected on one or both sides tothe connectors or commissure attachment features. The anchor featurescan be connected to the stent at a connector, proximal of the connector,or distally of the connector. Two or more anchor features can beconnected on each side to the same connector or commissure attachmentfeatures for a nested anchor feature configuration.

The engagement portion of the anchor feature can flare distally from thestent or proximally from the stent. A stent can include two anchorfeatures with engagement portions, with the engagement portion of oneanchor feature flaring distally from the stent and the engagementportion of one anchor feature flaring proximally from the stent.

The latch members can include a variety of materials. These includeanimal tissues, such as porcine, ovine and bovine pericardium or porcinesub-mucosa. These materials also include fabrics, such as knit or wovenpolyester and non-woven fabrics. These materials can further includecollagen and water-absorbing polymers such as poly(acrylic acid). Thematerials can still further include biocompatible adhesives such asepoxy amines. Still further, these materials can include bio-absorbablematerials such as polyglactin, copolymers of lactide and caprolactone,and polylactides.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic sectional view of the aortic root tissue in atypical human heart;

FIG. 2 is a perspective view of a prior art stent in an expandedconfiguration;

FIG. 3 is an enlarged elevational view of a portion of a stent withanchor features residing within closed cells of the stent;

FIG. 4 is a schematic of a stent, according to an embodiment of theinvention, deployed in a human heart.

FIG. 5A is a highly schematic fragmentary side view depicting a portionof a stent incorporating an anchor feature according to an embodiment ofthe invention;

FIGS. 5B-5F are highly schematic fragmentary side views depictingportions of stents incorporating an anchor feature engaged with a heartor with an implanted device within a heart according to embodiments ofthe invention;

FIGS. 6A-6E are highly schematic fragmentary views depicting portions ofstents according to further embodiments of the invention; and

FIG. 7 is a fragmentary elevational view of a portion of a stentaccording to an embodiment of the invention with a portion of anattached valve leaflet, and with certain features omitted for clarity ofillustration.

DETAILED DESCRIPTION

While the present invention will be described more fully hereinafterwith reference to the accompanying drawings, in which particularembodiments of stents and methods of delivery are shown, it is to beunderstood at the outset that persons skilled in the art may modify theinvention herein described while achieving the functions and results ofthis invention. Accordingly, the descriptions that follow are to beunderstood as illustrative and exemplary of specific structures, aspectsand features within the broad scope of the present invention and not aslimiting of such broad scope. Like numbers refer to similar features oflike elements throughout.

FIG. 1 is a simplified view of the geometry or anatomy of the aorticroot tissue in a typical human heart. The left ventricular outflow tract(LVOT) 1 communicates with the ascending aorta 5 through the annulus 2of the native aortic valve and the Valsalva sinus 3. The sinus joins theaorta at the sinotubular junction (STJ) 4. The native aortic valvetypically includes three native valve leaflets 6, of which only two arevisible in FIG. 1. As the left ventricle contracts during systole, bloodis forced from the LVOT 1 through the native valve and sinus and intothe aorta 5, moving generally in the downstream or antegrade flowdirection indicated by arrow D. In a healthy individual, the nativevalve leaflets 6 open away from one another and move to the positionschematically shown in broken lines at 6′ to permit flow in thisdirection. During diastole, when the ventricle is not contracting, thenative valve leaflets 6 move back to the position indicated in solidlines in FIG. 1, where they abut one another or “coapt” so as tosubstantially block flow in the upstream or retrograde direction,opposite to arrow D. The direction “distal” as used herein withreference to a feature of the native circulatory system refers to thedirection of antegrade flow, i.e., the predominant direction of bloodflow through such feature, as indicated by arrow D. The direction“proximal” as used herein with reference to a feature of the nativecirculatory system is the opposite direction.

The parameters identified in FIG. 1 are as follows: DO=orifice diameter,i.e., the interior diameter of native annulus 2; DA=the diameter of theaorta just distal to the sinus; DB=maximum projected sinus diameter(this sinus is sometimes known as the Valsalva sinus); LA=length of thesinus, i.e., the dimension in the distal direction from the annulus 2 tothe sinotubular junction 4; and LB=distance in the distal directionbetween DO and DB.

The leaflets 6 have distal edges 9 remote from the annulus 2. Eachnative leaflet 6 has a surface 7, referred to herein as the “interior”surface of the leaflet, facing generally towards the other leaflets.Each native leaflet 6 also has a surface 8, referred to herein as the“exterior” surface of the leaflet, facing outwardly, away from the otherleaflets and toward the wall of the sinus 3. The cross-sectional shapeof such a native valve varies somewhat from individual to individual,and this variation can be increased by various types of disease. Forexample, disease can reshape the cross-section of a patient's valve to acircular, triangular, or elliptical shape, depending on the diseasestate.

FIG. 2 shows a prior art collapsible stent for use with a prostheticheart valve. Examples of collapsible prosthetic heart valves aredescribed in U.S. Application Publication No. 2012/0053681 and U.S.Design Pat. No. D660,967, the entire contents of which are herebyincorporated by reference herein. An expandable stent body 10 is formedas a unitary structure as, for example, by laser cutting or etching atube of a superelastic metal alloy such as a nickel-titanium alloy ofthe type sold under the designation NITINOL. Such a unitary structurecan also be referred to as a “non-woven” structure, in that it is notformed by weaving or winding one or more filaments. In itsfully-expanded, unconstrained configuration, the illustrated embodimentof stent body 10 includes an annulus section 12, an aorta section 20 andsupport struts 30 extending between the annulus section and the aortasection. The annulus section 12 in the expanded configuration isgenerally in the form of a cylindrical tube having a central axis 14,whereas aorta section 20 is generally in the form of a hoop coaxial withthe annulus section. The annulus section 12 can be in the form of othershapes, such as elliptical or triangular, depending on the patient'sanatomy. Not all embodiments of stent body 10 include an aorta section20. For example, stents for aortic valves, as well as stents forbicuspid and/or mitral valves may not include an aorta section 20.

The stent body 10 is adapted for installation in the body of a patientwith the annulus section 12 adjacent the annulus 2 and with the aortasection 20 adjacent the sinotubular junction 4 and aorta 5. Thus, whenthe valve incorporating the stent body 10 is placed in the patient, theaorta section 20 will be disposed distal to the annulus section 12 inthe frame of reference of the patient's circulatory system. Accordingly,as used with reference to features of the stent body and valve, thedirection D (FIGS. 1 and 2) along axis 14 from the annulus section 12towards the aorta section 20 is referred to as the distal direction, andthe opposite direction is taken as the proximal direction. Statedanother way, the distal direction along the stent body is the directionfrom the end of the stent which is intended for disposition at aproximal location in the frame of reference of the circulatory system tothe end of the stent which is intended for disposition at a more distallocation in the frame of reference of the circulatory system. Also, theoutward direction as used with reference to the stent body is thedirection away from the proximal-to-distal axis 14. The directionstoward and away from axis 14 are also referred to herein as the “radial”directions. As used with reference to features of the stent body, the“circumferential” directions are the directions around axis 14.

As best seen in FIG. 2, the annulus section 12 includes numerous cellsdefined by interconnecting struts 16 which join one another atintersection points. These cells are disposed in a proximal row 70 anddistal row 60, each such row extending circumferentially around theproximal-to-distal axis 14 so that the cells cooperatively form agenerally cylindrical wall. In the expanded condition, the struts 16 ofeach cell form a generally diamond-shaped structure. In the unexpandedor collapsed configuration, the struts 16 of each cell extendsubstantially proximally and distally, so that each cell is collapsed inthe circumferential direction. The intersection points 18 between thestruts 16 on the distal side of distal row 60 define the distal edge ofthe annulus section 12. These intersection points are referred to hereinas the distal crests 18 of the annulus section 12.

The annulus section 12 also includes a set of commissure features 40formed integrally with the remainder of the stent body. The commissurefeatures 40 are found at three locations spaced equally around thecircumference of the annulus section. Each commissure feature 40 mayinclude one or more eyelets 120 therein. Three prosthetic valve leaflets(not shown) are sutured to the commissure features 40, so that theleaflets are disposed within the annulus section 12 of the stent body.The sutures (not shown) may extend through eyelets 120. A lining or“cuff” (not shown) may be provided on the interior surface, exteriorsurface or both of the annulus section 12, over all or part of the axialextent of the annulus section 12. The leaflets and cuff may be formedfrom conventional biocompatible materials such as synthetic polymers andanimal tissues such as pericardial tissues. Stent body 10 can includemore than three or fewer than three commissure features 40, for exampleto accommodate more or fewer than three valve leaflets.

Aorta section 20 is formed by a set of struts 16 which define a row ofhalf-cells. The configuration of the struts 16 in aorta section 20 maybe varied from that shown. For example, the aorta section 20 may includeone or more rows of full cells such as those constituting the annulussection 12. Also, the support struts 16 may have a branchedconfiguration, so that the distal end of each support strut is connectedto plural points in the aorta section 20. More or fewer support struts16 may be provided.

In one embodiment of the invention, best seen in FIG. 3, the stent body10 also includes anchor features in the nature of latch members 50. Thelatch members 50 are equally spaced from one another in thecircumferential direction and reside within adjacent closed cells 80.More specifically, the latch members 50 reside within the space of thedistal crests 18 and commissure features 40 of the annulus section 12and above the level of the leaflet belly 90 of the valve leaflet. Thelocations of the latch members 50 allow the stent body 10 to maintain asimilar or identical crimp profile as the stent body 10 would have inthe absence of the latch members 50. Alternatively, the locations of thelatch members 50 can be higher than the free edge of the prostheticleaflet (not shown) to avoid contact between the prosthetic leaflet andthe latch members 50 during crimping or other use. Although the highlyschematic embodiment illustrated in FIG. 3 has three latch members 50(two of which can be seen in the highly schematic view) equallydistanced around the circumference of the stent body 10, the number andlocation of latch members 50 is a matter of design choice. For example,alternate embodiments of a stent could include a single latch member 50or two or more latch members. The latch members 50 could also be spacedunequally around the circumference of the stent body 10. For example,for a stent to be used with a bicuspid valve, it may be preferable toinclude only two latch members 50 (i.e., one latch member per leaflet).Depending on the specific anatomy of the heart valve and native leafletsinto which the stent will be implanted, spacing between latch members 50other than equal spacing may be preferred. Further, the number of latchmembers 50 does not necessarily need to correspond to the number ofleaflets in the valve into which the stent is being deployed. Forexample, it may only be desired to utilize two latch members 50 in atricuspid valve. In this scenario, two valve leaflets would be engagedby latch members with the remaining leaflet unengaged by any latchmember. Additionally, latch members 50 do not need to reside in adjacentcells 80. Rather, one or more empty cells 80 (i.e. cells without latchmembers 50) could reside between cells with latch members.

The latch members 50 are connected on each side to either a distal crest18 or commissure feature 40. Each latch member 50 includes a pair ofconnection struts 54. Similar to the remainder of stent body 10, theconnection struts 54 are elongated solid members formed of asuperelastic metal alloy such as a nickel-titanium alloy and can be ofany cross sectional shape such as circular or oval. The connectionstruts 54 can be formed of other materials, or additional materials,such as polymers, bio-absorbable materials, drug eluting materials, orfabric coatings to enhance tissues in-growth. These and other materialsare discussed more completely below. Each connection strut 54 connectsto either a distal crest 18 or a commissure feature 40. Each latchmember 50 also includes a generally U- or V-shaped intermediate globalportion 57 joined between connection struts 54. The latch members 50,including connection struts 54 and intermediate global portion 57, canbe formed integrally with the remainder of stent body 10. For example, asingle tube of a superelastic metal alloy can be laser cut or etched,forming the entire stent body 10, including the latch members 50, fromthe original single tube. Alternately, the latch members 50 can beformed separately from the stent body 10 and can later be connected tothe stent body, for example by welding, suturing, gluing or othermethods.

In the expanded configuration of the stent body 10, U-shaped portion 57slopes radially outwardly so as to be disposed radially outward of thedistal end of annulus section 12. The U-shaped portion 57 lies at thedistal end of the annulus section 12.

The structure of the latch member 50 allows it to collapse in the radialdirection. Thus, in the collapsed configuration of the stent body 10,the connection struts 54 and U-shaped portion 57 extend substantiallyaxially.

In operation, the valve is brought to a collapsed condition and mountedon a delivery device (not shown) such as an elongated probe having asheath adapted to retain the stent body in the collapsed condition, andhaving provisions for moving the sheath relative to the stent body torelease the stent body from the sheath. The delivery device is advancedinto the patient's body until the valve is aligned with the nativeaortic valve, with the annulus section 12 adjacent the annulus 2 of theaorta. The valve is released from the sheath and stent body 10 expandsunder its own resilience. The resilient expansion may occur solely as aresult of release of mechanical constraint of the stent body, or mayinclude expansion resulting from the effects of temperature change onthe material of the stent body. Preferably, the entire expansion of thestent body from its collapsed condition to its expanded, operativecondition is brought about by the stent body itself. Stated another way,the stent body desirably is fully self-expanding and does not require aballoon or mechanical movement device to bring about any part of theexpansion. Referring to FIGS. 1 and 4, the annulus section 12 engagesthe annulus 2 of the native aortic valve, and also engages the interiorsurfaces 7 of the native valve leaflets 6. Each latch member 50 engagesone of the native valve leaflets 6 at or near the distal edge 9 of suchnative leaflet. The U-shaped portion 57 (not labeled in FIG. 4) of eachlatch member 50 upon expansion bears on the exterior surface 8 of theleaflet 6 at or near the distal edge. In other words, the native valveleaflets 6 are clamped between the latch members 50 and the remainder ofthe stent body 10. It should be appreciated that the leaflets 6typically have irregular shapes. For example, the leaflets 6 may benodular or rough. The aorta section 20 engages the native anatomy at ornear the sinotubular junction 4.

Although the stent reaches an expanded configuration, it typically doesnot reach its fully-expanded, unconstrained configuration. Thus, theresilience of the stent body normally causes the aortic section 20 tobear on the sinotubular junction 4 and also causes the annulus section12 to bear on the annulus 2 and on the interior surfaces of theleaflets. The prosthetic valve leaflets open to allow distal orantegrade flow of blood during systole, and close to block proximal orretrograde flow during diastole. The engagement of the latch members 50with the native valve leaflets 6 helps to maintain the stent body 10,and hence the valve, in position. In particular, such engagement helpsto prevent movement of the valve in the proximal or retrogradedirection. Therefore, the resilient engagement of the annulus section 12and aorta section 20 with the native anatomy need not provide all of theforce necessary to resist such movement. Moreover, the engagement of thelatch members 50 with the native valve leaflets 6 tends to bias thenative leaflets 6 inwardly toward the annulus section 12 of the stentbody 10. This tends to improve sealing between the native leaflets 6 andthe stent body 10 and helps to resist perivalvular leakage or retrogradeflow around the outside of the stent body. The latch members 50facilitate satisfactory valve action without the need for extremely highradial forces between the annulus section 12 of the stent body 10 andthe native valve anatomy. This is advantageous, inasmuch as excessiveradial forces on the native anatomy may disrupt the electricalconduction system of the heart and or distort the mitral valve, which isdisposed near the annulus 2 of the aortic valve.

The latch members 50 may be altered in a variety of ways to furtherreduce PV leakage, especially near points of contact between the nativeleaflets 6 and the latch members 50. The latch members 50 can includematerials such as animal tissues as, for example, porcine, ovine andbovine pericardium, porcine sub-mucosa, and synthetic fabrics such asknit or woven polyester, and non-woven fabrics. Collagen-impregnatedfabrics may be used. Also, bio-absorbable materials such as polyglactin,copolymers of lactide and caprolactone, and polylactides can be used.

Latch members 50 covered in fabrics, for example, can promote tissuein-growth. As tissue grows into the fabric of the latch members 50, abetter seal is created at the sites of the latch members 50, reducingthe likelihood of PV leakage. Other alternatives to fabric that producetissue in-growth at the site of the latch members 50 can also reduce PVleakage.

Latch members 50 alternatively can include a hygroscopic or sponge-likematerial that collapses easily and fills to a larger volume when thestent is expanded after implantation. This hygroscopic material, forexample, can be a collagen foam or sponge similar to the materialcommercially available under the trademark Angioseal which is used toplug arteries, and to the similar material currently used for embolicprotection.

In a further embodiment, material on the latch members 50 can beimpregnated with a water-absorbing polymer. When allowed to expand as aresult of implantation in a patient and consequent absorption of waterfrom the patient's tissue and/or blood, these materials can fill anygaps between the latch members 50 and the native tissue to reduce PVleakage.

In still further embodiments, mechanical means, such as small coil ortorsion springs, can be used as alternate or additional means to fillany gaps between the stent body 10 and the native tissue to reduce PVleakage. The mechanical means can be formed integrally with the stentbody 10. For example, springs formed integrally with the stent body canproject outwardly from the stent body 10 in the expanded condition,biasing the cuff outwardly toward the native tissue. Other mechanicalmeans include coil springs that have a spring axis extending generallyin a radially outward direction from the stent body 10. Such small coilsand torsion springs are described more fully in U.S. Patent ApplicationPublication No. 2011/0098802, the entire contents of which are herebyincorporated by reference herein.

The latch members 50 of the stent body 10 can be made to be bonded tonative tissues as, for example, to native leaflets 6 during or afterimplantation. For example, a porcine pericardial strip on the latchmembers 50 can be used to bond a tissues-to-tissue joint. The bondingcan be achieved, for example, by lower power lasers that minimize tissuevaporization, yet bond tissue together. Biocompatible adhesives, such asepoxy amines, have been applied in certain medical applications. Suchadhesives can be applied around the perimeter of the latch members 50 tobond to native leaflets during or after implantation. These and othervariants, as applied to a cuff of a prosthetic valve rather than latchmembers of a stent body, are described more fully in U.S. PatentApplication Publication No. 2011/0098802.

The resilience of the latch members 50 allows them to attach to bothcalcified and non-calcified leaflets 6. For example, if a leaflet 6 isthick, nodular or both, the U-shaped portion 57 of the latch member 50can be bent outwardly by the leaflet 6. In this condition, the latchmember 50 tends to push the leaflet 6 inwardly against the annulussection 12 of the stent body 10. The systolic blood pressure tends toforce the native valve leaflets 6 into engagement with the annulussection 12 of the stent body. By retaining the native leaflets 6 inposition, the latch members 50 facilitate this action.

The prosthetic valve allows antegrade flow into the aorta, and alsoallows flow into the Valsalva sinus and thus into the coronary arteriesC which communicate with the sinus. Engagement of the native valveleaflets 6 by the latch members 50 may help to assure that the nativevalve leaflets 6 do not block the openings of the coronary arteries.

Various embodiments of latch members 50 can be used in conjunction witha stent having a closed cell design. FIG. 5A shows a side view of anembodiment of a latch member 50 along with the portion of the stent body10 on which the latch member 50 is located. For simplicity ofillustration, only a portion of the stent body 10 is depicted. The latchmember 50 generally flares radially outward from the stent body 10 andalso extends proximally from the points of attachment of the stent body10 between distal crest 18 and commissure feature 40 (not visible inFIG. 5A). The location of the latch member 50 within the space betweenthe distal crests 18 allows for the latch member 50 to be compressedradially inward in the direction of the arrow R shown in FIG. 5A.Additionally, the direction in which latch member 50 flares allows forthe resheathability of the stent body 10. In the event that the proximalend of stent body 10 emerges from a deployment device (not shown) beforethe distal end of the stent body, the proximal end of the stent bodywill expand first while the distal end of the stent body remains withinthe deployment device. If repositioning becomes necessary, the directionin which latch member 50 flares will not hinder stent body 10 from beingresheathed into the deployment device.

FIG. 5B shows the stent body 10 illustrated in FIG. 5A after it has beenimplanted into a patient. In this embodiment, the flared portion oflatch member 50 engages a native leaflet 6 of the native heart valve.Referring now to FIGS. 5C-5F, there are shown side views of differentembodiments of stent body 10 with latch members 50 implanted in theheart tissue of a patient. FIG. 5C shows an embodiment of stent body 10with a latch member 50 that flares in substantially the oppositedirection to that shown in FIG. 5B. In this embodiment, the latch member50 flares distally from the stent body 10. This configuration allows thelatch member 50 to primarily engage the tissue at the sinotubularjunction 4. Engagement of the sinotubular junction 4 aids the stent inresisting migration in the distal direction. Additionally, the directionin which the latch member 50 flares allows resheathing of the stent ifthe distal end of stent body 10 is deployed from the delivery device(not shown) before the proximal end.

FIG. 5D shows another embodiment of stent body 10 with a pair of latchmembers 50, 50′. The distally flaring latch member 50 engages thesinotubular junction 4, while the proximally flaring latch member 50′simultaneously engages a leaflet 6 of the native heart valve. Thisconfiguration allows for added anchoring capability from the use ofmultiple latch members.

FIGS. 5E and 5F each show embodiments of stent body 10 with latchmembers 50 that do not primarily engage native heart tissue. In theembodiments shown in FIGS. 5E and 5F, the latch members 50 are similarto that shown in FIG. 5B in that the latch members flare outwardly in aproximal direction. However, in the embodiment shown in FIG. 5E, thelatch member 50 engages a surgical valve 200 that has already beenimplanted in the patient rather than a native heart structure. In theembodiment shown in FIG. 5F, the latch member 50 engages stent featuresof another transcatheter aortic valve implant 250, such as between opencells 252 of the second implant. Latch members 50 can be designed tocorrespondingly mate to a device already implanted in the heart, such assurgical valve 200 or stent 250, depending on the specific features ofthe device already implanted in the heart. For example, if the surgicalvalve 200 is thicker than an average native leaflet, the latch member 50could be designed to extend initially more radially outward to ensurethat the latch member sufficiently engages or “hooks” the surgicalvalve, as seen in FIG. 5E. Similarly, for latch members 50 to engagecells of another stent 250, such as that shown in FIG. 5F, the latchmembers may extend farther or less far in the proximal or distaldirections, may flare distally or proximally, or may extend at a more orless acute angle. The specific design of the latch members 50 willdepend on the corresponding features of the already-implanted device.Also, as described above, the latch members 50 can be covered with anyof a variety of materials. For latch members 50 that primarily engageother implanted devices, especially metal devices, it may be desirableto provide a fabric or other coating on the latch members to avoidmetal-on-metal contact. In the absence of a coating on the latch members50, the metal-on-metal contact could cause, for example, frettingcorrosion, abrasion, or other types of corrosion or wear.

As mentioned above and shown in the embodiment illustrated in FIG. 3,the central portion 57 of the latch member 50 may be generally “U”shaped. Other shapes are within the scope of the invention and may beselected depending on the specific anatomy of the patient. Differentembodiments of the central portion are illustrated in FIGS. 6A-6E. Forexample, FIG. 6A illustrates a central portion 510 with a very narrow oracute “V” shape. The central portion 520 of FIG. 6B is generally “U”shaped, but with a squared off or blunted tip. FIG. 6C shows a centralportion that consists of two separate pieces 530, as opposed to thecontinuous central portions shown in FIGS. 6A-B. Other possible shapesof the central portion of latch member 50 include, but are not limitedto, central portions with blunt piece 540 and a separate circular piece545 as seen in FIG. 6D, and a central portion having a generally acute“V” shaped portion 550 with a blunt extension piece 555 as shown in FIG.6E.

The choice of a particular shape for the central portion of latch member50 may be based on a number of factors, such as particular types oftrauma existing in the patient's heart tissue, the need forresheathability of the stent, and the specific type of interface withwhich the latch member central portion will engage. For example, a latchmember 50 having an acute “V”-shaped central portion 510 would applyrelatively high force at the point of engagement. However, if aparticular patient would be at a high risk of having his cardiac tissuepierced by such relatively high force, a blunted central portion 520might be more appropriate as it would distribute the applied forcesacross a larger area. In patients with nodules of calcification on theirnative heart valves, for instance, the central portion with separatepieces 530 may provide the greatest flexibility for optimal engagementof the latch member to the site of engagement. Similarly, the latchmember with separate blunt pieces 540 and 545 shown in FIG. 6D couldprovide greater flexibility for maintaining contact with irregularsurfaces and still provide a relatively large area over which thecontact forces may be distributed. When engaging a previously existingimplant, such as another transcatheter aortic valve implant, the latchmember central portion may be shaped to enhance engagement capabilitiesbased on the specific shape of the previously existing implant.

Although specific embodiments of latch members 50 have been described,other sizes and shapes are within the scope of the invention. Forexample, latch members 50 with larger or smaller cross sections may beused to provide different levels of resilience. Further, shapes notdiscussed above may been implemented, for example, to match thecondition of the patient's native valve leaflets 6 as measured, forexample, by imaging techniques before or during the procedure. A kitincluding different valves with stent bodies having different latchmembers may be provided to facilitate such selection.

FIG. 7 shows a continuous run of stent cells 600 within a portion ofstent body 10 to illustrate, but not limit, different attachmentlocations of the latch members 50. For example, the latch members 50 maybe attached at one end to a commissure attachment feature 40 to which avalve leaflet 90 may also be attached, or above or below such commissurefeature, and at the other end to a distal crest 18 (this configurationnot shown in FIG. 7). The latch members 50 may also be attached at bothends to the distal crests 18, or above or below such distal crests.Additionally, multiple connections per distal crest 18 or commissureattachment feature 40 are possible to create nested latch members 50within a single cell, as illustrated in FIG. 7. Preferably, theconnections are made far enough distally of the leaflet belly 90 and thefree edge 92 of the leaflet to avoid contact between the latch members50 and the leaflets as the leaflets open and close and as the stent body10 is crimped or expanded.

Numerous other variations and combinations of the features describedabove may be employed. For example, features described in one or moreembodiments may be combined with the features described in otherembodiments. The cellular structure of the stents described above mayalso be varied. For example, the features described above may beemployed in woven stent bodies and in stent bodies which are not fullyself-expanding as, for example, stent bodies which are forcibly expandedby a balloon or mechanical device during implantation.

Although the foregoing most frequently refers to prosthetic aorticvalves, it will be appreciated that prosthetic valves in accordance withthis invention may be used for other cardiac valves. As just one exampleof this, elliptical prosthetic valves in accordance with the inventionmay be used as prosthetic mitral valves.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It is therefore to be understood that numerousmodifications may be made to the illustrative embodiments and that otherarrangements may be devised without departing from the spirit and scopeof the present invention as defined by the appended claims.

The invention claimed is:
 1. A method of implanting a prosthetic heartvalve comprising: positioning a prosthetic heart valve in a collapsedcondition within a sheath of a delivery device, the prosthetic heartvalve including a stent having (i) a plurality of struts forming cellsand (ii) an anchor feature with a first end coupled to a first portionof one of the cells and a second end coupled to a second portion of theone of the cells; advancing a sheath of a delivery device to a patient'snative valve, the sheath retaining the prosthetic heart valve in thecollapsed condition so that (i) no portion of the anchor featureoverlaps in a radial direction of the stent with any of the plurality ofstruts forming the cells and (ii) the first end and the second end ofthe anchor feature are spaced apart by a first distance; releasing theprosthetic heart valve from the sheath; transitioning the prostheticheart valve from the collapsed condition to an expanded condition sothat the first end and the second end of the anchor feature are spacedapart by a second distance greater than the first distance; engaging theanchor feature to a surface of a heart of the patient; and releasing theprosthetic heart valve from the delivery device.
 2. The method of claim1, wherein the step of engaging the anchor feature to a surface of theheart includes engaging the anchor feature to at least one of a portionof a leaflet of the native valve or a portion of a sinotubular junctionof the heart.
 3. The method of claim 1, wherein after the step ofengaging the anchor feature to the surface of the heart and prior toreleasing the prosthetic heart valve from the delivery device, theanchor feature is oriented at an oblique angle to a longitudinal axis ofthe sheath so that the stent may be resheathed.
 4. The method of claim3, wherein the anchor feature slopes radially outwardly from the stentwhen the stent is in the expanded condition.
 5. The method of claim 3,wherein the anchor feature is parallel to a longitudinal axis of thestent when the stent is in the collapsed condition.
 6. The method ofclaim 1, wherein the step of engaging the anchor feature to a surface ofa heart of the patient includes simultaneously engaging both a portionof a leaflet of the native valve and a portion of a sinotubular junctionof the heart.
 7. The method of claim 1, wherein the step of engaging theanchor feature to a surface of a heart of the patient includes engagingthe anchor feature to a device implanted in the patient's heart.
 8. Themethod of claim 1, wherein the anchor feature includes an anchor tipbetween the first end and the second end.
 9. The method of claim 8,wherein the anchor tip has a sharp “V” shape.
 10. The method of claim 8,wherein the anchor tip is blunted.
 11. The method of claim 8, whereinthe anchor tip includes at least two separate pieces.
 12. The method ofclaim 11, wherein at least one of the at least two separate piecesincludes a blunted end.
 13. The method of claim 1, wherein the cells ofthe stent include a first annular row of cells connected to a secondannular row of cells by at least one connector, the anchor feature beingcoupled to the at least one connector.
 14. The method of claim 13,wherein the at least one connector is a commissure attachment feature.15. The method of claim 14, wherein at least two anchor features areeach coupled at the first end of the anchor feature to a first connectorand are each coupled at the second end of the anchor feature to a secondconnector to form a nested anchor feature configuration.
 16. The methodof claim 1, wherein the cells of the stent include a first annular rowof cells connected to a second annular row of cells by at least oneconnector, the first end of the anchor feature being coupled to thestent body between an inflow end of the stent and the at least oneconnector.
 17. The method of claim 1, wherein stent cells include afirst annular row of cells connected to a second annular row of cells byat least one connector, the first end of the anchor feature beingcoupled to the stent between an outflow end of the stent and the atleast one connector.
 18. The method of claim 1, wherein after the stepof engaging the anchor feature to the surface of a heart of the patient,an engagement portion of the anchor feature flares toward an outflow endof the stent.
 19. The method of claim 1, wherein after the step ofengaging the anchor feature to the surface of the heart of the patient,an engagement portion of the anchor feature flares toward an inflow endof the stent.
 20. The method of claim 1, wherein the anchor featureincludes a first anchor feature and a second anchor feature, and afterthe step of engaging the anchor feature to the surface of the heart ofthe patient, an engagement portion of the first anchor feature flarestoward an inflow end of the stent and an engagement portion of thesecond anchor feature flares toward an outflow end of the stent.
 21. Themethod of claim 1, wherein the anchor feature spans circumferentiallyacross the one cell.
 22. The method of claim 1, wherein in the expandedcondition of the heart valve, no portion of the anchor feature ispositioned radially inward of the one cell.